The present invention relates in general to metal drum fabrication and the insertion die tooling associated with this fabrication. The present invention more specifically relates to the configuring of the drum end with an installed, internally-threaded flange and the associated insertion die tooling. The referenced flange is constructed and arranged for receipt of an externally-threaded closing plug. The present invention relates to the construction and arrangement of the insertion die tooling and modifications to that tooling that relate directly to the installation of the flange into an embossment formed in the metal of the drum end.
Prior to loading the drum end onto a corresponding work station of the insertion die tooling, the metal drum end is formed with the embossment which provides a shaped annular pocket that is constructed and arranged to receive the flange. Thereafter, in terms of the fabrication sequence, the metal of the drum end is formed over, under, and around the flange so as to securely anchor the flange into the drum end. This basic construction method and configuration is well known in the industry and represents technology that has been practiced for several years. Traditionally, the initial forming of the drum end pocket or embossment included an outer annular wall that had a generally cylindrical shape and an upper, substantially planar panel that was substantially perpendicular to the outer annular wall. In this final configuration, the drum end material does not extend into the open interior defined by the flange outer wall.
This flange and drum end construction and structural relationship is described generally in U.S. Pat. No. 5,943,757, in the context of a new one-step insertion die. The '757 patent issued Aug. 31, 1999 to Magley and is incorporated by reference herein in its entirety. One difference between the '757 patent and prior art fabrication methods and tooling is the forming of the embossment as one step in the overall sequence as contrasted to having that embossment pre-formed in the drum end prior to loading the drum end onto the lower work station. Importantly, in the context of the present invention, neither the '757 patent nor the prior art installation constructions for metal flanges disclose any inner axial wall being formed as part of the drum end. The reference to “inner” refers to an axial wall being formed on the inside of the flange. While the basics of the crimping procedure so as to install a flange into the drum end pocket or embossment are believed to be well known, this fabrication is performed without the use of any inner axial wall for these types of metal flanges.
In U.S. Pat. No. 4,588,103, a plastic closure (20), shaped as an internally-threaded flange, is installed into boss (41) that is formed in the metal drum end (42) as illustrated in FIG. 2 of the '103 patent. The insertion tooling illustrated in FIG. 5 of the '103 patent includes a center holding and forming die (53) which is of annular shape and contoured along its lower surface so as to fit snugly up against upper wall (45) after forming inner wall (44) of boss (41). Inner wall (44) and outer wall (43) are substantially concentric with one another. Center annular portion (55) helps to form inner wall (44) and is positioned against inner wall (44) as the crimping members or collets (54) act on boss (41). Importantly, the center annular portion (55) is cylindrical.
In U.S. patent application Ser. No. 10/971,874, filed Oct. 22, 2004 and published Dec. 8, 2005 as Publication Number US-2005-0269330-A1, an inner annular wall is formed in a metal drum end as a part of the overall insertion construction for a metal, internally-threaded flange. The forming of the drum end includes shaping an outer annular wall that is generally cylindrical, an upper, generally planar panel, and the inner wall. As illustrated in FIG. 10 of the '874 application, the inner wall (27) is inwardly and downwardly tapered into a frustoconical form. The insertion of the metal flange into the drum end and its final installation involves the application of opposing inner and outer forces directed against portions of the drum end material.
The present disclosure is directed to an improvement in the insertion die tooling by changing the cylindrical form of the center annular portion or pilot into a frustoconical form. As one example of a pilot, refer to portion (55) in the '103 patent. This same modification, according to the present disclosure, would be applicable to any prior art insertion die tooling where a cylindrical center form or pilot is used for the shaping of a generally cylindrical inner wall. This particular change in the insertion die tooling results in an improved structure as compared to an inner tooling form that is cylindrical. One benefit derived from the present disclosure is the ability to change the thickness of the drum end material without having to change the insertion die tooling for proper installation of the flange.